The present invention relates to a device for use with a liquid tank for a vehicle, in particular a device for supporting and securing the liquid tank on the vehicle in the form of at least one supporting bracket fixed to the vehicle and provided with members for locating and securing the tank to the supporting bracket, and to a tank having locating members for facilitating mounting and fixing of the tank to the supporting bracket.
Liquid tanks for heavy vehicles, especially fuel tanks and the like for heavy goods vehicles, are usually configured in substantially cylindrical form with two end faces and an intermediate shell surface. There are two main types of tanks available on the market, one of which has circular-cylindrical cross-section, hereinafter referred to as a circular tank, and the other of which has a rectangular-cylindrical, hereinafter referred to as a rectangular tank. In addition, an alternative type of tank forms a combination of the circular and rectangular tank, resulting in an asymmetrical or D-shaped cross-section.
One advantage with a circular tank is that, owing to its round tank bottom shape, it has a minimal volume of residual liquid, that is, the liquid which can never be drawn out of the tank as a result of the suction tube of the tank being located, by necessity, at a certain distance from the bottom of the tank. A further advantage with the circular tank is that it is fastened to the vehicle frame by two relatively compact and weight-saving supporting brackets. Brackets of this type offer good ground clearance by virtue of being designed as a vertical cradle having a part-circular bearing surface for the tank. The supporting brackets are provided with fixtures for straps, by which the circular tank is forced in against the cradles of the supporting brackets.
Circular tanks have the drawback that they offer a smaller liquid capacity. They may also mm the risk of rotating relative to the fastening arrangement, thereby generating stresses upon the tank fittings, such as connecting elements for connecting pipes to the tank. Because of their circular shape, these tanks require no special positioning during mounting onto the vehicle, since they can easily be rotated into the correct position before being clamped in place.
One widely adopted solution for supporting a tank, especially for heavy vehicles, is to utilize an L-shaped supporting bracket. This bracket reaches in beneath the tank and cooperates with straps which are fastened at the outer ends of the supporting bracket and which, together with the bracket, embrace the tank in order to secure it to the bracket. The tank is in this case usually rectangular, with corner portions which are somewhat rounded. In this type of supporting bracket, the part reaching in beneath the tank requires space in the vertical direction, which means that the total space for tank and bracket cannot be utilized effectively for the storage of liquid, since the ground clearance requirement limits the space downward. One advantage with the rectangular tank is that, precisely by virtue of its rectangular shape, it has no tendency to rotate in its fastening during travel.
A further solution is constituted by an asymmetrical, for example D-shaped, tank, in which the part of the tank which bears against a bracket fixed to the vehicle has a cylindrical, oval or similar rounded shape. These embodiments are below termed “part-circular”. Such a tank is able to combine the advantages of the abovementioned tank types. Owing to its extent transversely to the longitudinal axis of the vehicle, the tank must, however, be accurately positioned when mounted and must be clamped in place such that it cannot be turned or rotated in any direction, since a small turn in connection with the bracket can produce a relatively large displacement of the outer end of the tank.
The present invention aims to provide an improved fastening arrangement for a liquid tank for a vehicle, which fastening arrangement will simplify mounting and fixing of the tank to a bracket on the vehicle. The invention further aims to provide a tank that allows the available volume for the storage of liquid to be maximized.
It is desirable to provide a fastening arrangement for use with a liquid tank, which arrangement allows for maximum utilization of the available space for the storage of liquid. It is also desirable to provide a fastening arrangement that allows the liquid tank to be easily mounted and subsequently held securely fixed in a predetermined position. The tank is preferably, but not necessarily, intended for some form of propellant for the vehicle engine or an auxiliary engine, urea for the after-treatment of exhaust gases, water or other liquids.
According to aspects of the invention, a liquid tank is provided and according to another aspect a fastening arrangement is provided.
According to a preferred embodiment, the invention relates to a liquid tank for a heavy vehicle, suitable for fastening to a vehicle frame by at least one supporting bracket having shaped surfaces suitable for load bearing and locating contact against said liquid tank, which the tank comprises two end face portions and a shell portion with a non-symmetrical cross-section extending there between. The tank may comprise a first, shaped portion facing the vehicle frame, arranged for load bearing contact against a first shaped surface of the supporting bracket, a second, shaped portion extending partially below said frame, arranged to locate the tank relative to a second shaped surface of the supporting bracket, and a third, substantially rectangular portion facing away from the vehicle frame. In this case, the term “substantially rectangular” is intended to include shapes ranging from a standard rectangular shape, with or without rounded corners, to a general rectangular shape, having rounded corners and curved outer side surfaces. The tank may be fastened to the supporting bracket by at least one clamping means.
The first, shaped portion of the tank may have an upper section arranged to take up a substantially horizontal load between the tank and the first shaped surface of the supporting bracket. In addition, the first, shaped portion of the tank may have a lower section arranged to take up a substantially vertical load between the tank and the first shaped surface of the supporting bracket.
The shaped portion of the tank is arranged to substantially conform to cooperating contact surfaces on the supporting bracket. This may be achieved by providing the tank with a recess having substantially the same shape as at least a part of an outer and/or lower portion of the supporting bracket. The recess in the tank may extend at least along the horizontal extension of the supporting bracket. On either side of the recess required for load bearing contact with the bracket, the tank may extend in close proximity to, but not in contact with, the frame. The vertical extent of the recess is also determined by the shape of the supporting bracket.
According to a further embodiment, the first, shaped portion of the tank may have a lower section provided with an indentation, extending an additional distance into the tank with respect to said recess, for cooperation with a corresponding protrusion on at least a lower section of the first, shaped portion of the supporting bracket.
Both the recess and the indentation can be shaped during the manufacture of the tank, for example by injection moulding of a plastics tank. Alternatively, the recess can be made during manufacture of the tank, while the indentation can be shaped subsequently, for instance by means of a heated tool having the basic shape of the supporting bracket.
In this context, terms such as “inner” or “towards” and “outer” or “away from” are to be interpreted as directions in relation to the vehicle frame onto which the tank is attached. The frame may comprise a beam having cross-section in the form of a C-profile, a closed profile or any other suitable profile having a substantially vertical section or surface facing away from a longitudinal central axis through the vehicle and a substantially horizontal lower section or surface.
The second, shaped portion of the tank extending partially below said frame may be arranged to locate the tank relative to the second shaped surface of the supporting bracket. This may be achieved by providing the tank with a substantially horizontal or slightly curved surface facing a correspondingly shaped lower surface on the supporting bracket. These corresponding surfaces are not required to take up any substantial forces relating to the weight of the tank, as their main function is to locate the tank during mounting and preventing it from rotating when clamped onto the supporting bracket. Both below and on either side of the supporting bracket, the tank may extend below said frame up to a vertical plane delimiting an inner longitudinal surface of the frame or the profile making up the frame.
In order to prevent the tank from deforming or buckling when being clamped to the bracket the tank is provided with a substantially vertical supporting wall around at least parts of its internal circumference adjacent each bracket. This wall may also be used to prevent the liquid from surging between the ends of the tank. The extension of the radial wall into the tank may vary around the circumference of the tank. For instance, adjacent to the lower part of the tank, the wall may be relatively low or be provided with apertures in order to allow liquid to flow towards a suction conduit extending into the tank. The lower end of the suction conduit is preferably located at the lowest point of the tank, to allow a maximum volume of liquid to be removed. The lowest point of the tank may be located in a recess in the tank, which recess can extend below the main part of the lower surface of the tank.
The tank is fastened to the bracket by a clamping means attached to the supporting bracket and extending around the outer circumference of the tank. The clamping means may be a flexible steel band or a similar suitable means. Attachment points for the clamping means may be provided on or adjacent an upper part of the supporting bracket, such as the upper section of the first, shaped portion thereof, and on or adjacent a lower part of the supporting bracket, such as an inner section of the second shaped surface of the supporting bracket.
Alternatively, the tank may be fastened to the bracket by a first clamping means extending over the tank from the upper part of the supporting bracket to an outer, lower corner of the substantially rectangular portion of the tank. A second clamping means may be provided extending under the tank from the lower part of the supporting bracket to the outer, lower corner of the third, substantially rectangular portion.
In order to locate the clamping means, recesses for said means may be provided adjacent at least one upper or lower outer corner of the substantially rectangular portion of the tank. Such locating means prevents the tank from moving in its longitudinal direction after mounting and fixing.
The invention further relates to a fastening arrangement for supporting a liquid tank on a frame for a heavy vehicle, which fastening arrangement comprises at least one supporting bracket having shaped surfaces arranged for load bearing and locating contact against said liquid tank, which the tank comprises two end face portions and a shell portion with a non-symmetrical cross-section extending there between, as described above. The supporting bracket may be attached to a substantially vertical surface of the vehicle frame and may comprise a first, shaped portion. The first portion may be arranged for load bearing contact against a first shaped surface of the tank. The supporting bracket may be in contact with a lower surface of said frame and may comprise a second, shaped surface arranged to extend partially below the frame and to locate the tank relative to a second shaped portion of the tank. Attachment means may be provided for fastening the tank to the bracket by at least one clamping means.
The first, shaped portion of the supporting bracket may have an upper section arranged to support a substantially horizontal load between the supporting bracket and the first shaped surface of the tank. The upper section of the first, shaped portion of the supporting bracket may be substantially parallel to or angled downwards and away from the frame. Alternatively, the upper section may be curved a short distance downwards and towards the frame towards a transition point between the upper section and a lower section. At this point the supporting bracket has a minimum cross-sectional thickness in a vertical plane at right angles to the longitudinal direction of the frame.
The first, shaped portion of the supporting bracket may further have a lower section arranged to support a substantially vertical load between the supporting bracket and the first shaped surface of the tank. At least this lower section may be arranged to extend into a corresponding recess in the tank. The lower section of the first, shaped portion of the supporting bracket may be angled downwards and away from the frame at angle of 30-50°. Alternatively the lower section may be curved downwards and away from the frame, in a vertical plane at right angles to the longitudinal direction of the frame, up to an angle in the said interval of 30-50°.
The second, shaped portion of the supporting bracket may be arranged to extend at least partially below said frame, in contact therewith, and may be arranged to locate the tank relative to the second shaped surface of the tank. In order to prevent chafing or damage to the tank when mounted, a smooth, rounded or curved transition section may be provided between the first and second shaped portions of the supporting bracket.
According to a further embodiment, the first, shaped portion of the supporting bracket has a lower section provided with a protrusion for cooperation with a corresponding indentation in the tank. This indentation may extend a further distance into the tank relative to the recess. The protrusion is preferably, but not necessarily located at or above the transition section between the first and second shaped portions.
By providing the liquid tank with shaped, load bearing surfaces adjacent each supporting bracket on the frame of the vehicle, said bracket can be made relatively small and compact. As the supporting bracket only extends a relatively short distance away from the side and lower surface of the frame, said bracket imposes minimal restrictions on the volumetric capacity of the liquid tank. In this way, the volume of a single, unitary tank can be maximized by allowing it to follow the outer contours of the side and lower surface of the frame, and to extend underneath at least parts of the vehicle frame. This arrangement allows the capacity of the liquid tank to be increased by at least 25% as compared to a standard D-shaped tank with the same longitudinal extension along the vehicle frame.
The first, shaped portion of the supporting bracket may be attached to a substantially vertical section of frame. The attachment may be achieved by any suitable means, such as a bolt and nut connection, riveting or welding.
The second, shaped portion of the supporting bracket is preferably, but not necessarily resting against the lower surface of the frame. Alternatively the second, shaped portion may be attached to the lower, substantially horizontal section of the frame. The attachment may be achieved by the means listed above, or by attaching or hooking the inner section of the supporting bracket is around an inner edge of a lower, substantially horizontal section of the frame.
Mounting a liquid tank a tank according to the invention, using one or more flexible clamping elements cooperate with supporting brackets for fastening the tank to the vehicle, can be achieved as follows. After attaching the supporting brackets to the frame, the tank is lifted into bearing contact against the first, shaped portions supporting brackets. The tank is then turned inwards and upwards about a longitudinal axis along said first, shaped portions until the second, shaped portions of the tank engages with the corresponding second, shaped portions supporting brackets so as to position the tank in a predetermined position. Finally, clamping elements are fastened to each supporting bracket and tightened around the tank. In order to prevent the tank from collapsing when the clamping elements are attached, the tank may be provided with internal supporting walls. Such supporting walls are preferably, but not necessarily, arranged as substantially vertical walls provided adjacent at least each supporting bracket. These walls may also act as baffles in the tank, to prevent the fluid from sloshing between the ends of the tank. At the same time, the walls should not prevent liquid from flowing towards the lowest point of the tank. A supporting wall of this type may comprise a solid vertical wall, having openings at a number of suitable locations, or have the shape of a rib or wall of varying extension from the inner peripheral surface of the tank.
Alternatively, the supporting brackets may be fastened to the tank in advance, whereby the assembled tank and brackets can be mounted at a predetermined location on the frame as a unit.
If the locating member is suitably dimensioned, a tank can be positioned and secured with just one such member. However, the number of supporting brackets is dependent on the size and location of the tank. For instance, two or three supporting brackets are commonly used for attaching a fuel tank for a commercial vehicle such as a truck.